ICD-10 Code S82.456C: Nondisplaced comminuted fibula shaft fracture

Key takeaways

ICD-10 code S82.456C covers a nondisplaced comminuted fracture of the fibular shaft, initial encounter, with a Gustilo type IIIA, IIIB, or IIIC open wound.

The sixth character 6 means the side was never documented. Use S82.454C for the right fibula and S82.455C for the left whenever the record names a side.

Comminuted means three or more bone fragments. Nondisplaced means those fragments stayed in anatomic alignment, which the radiology report has to state outright.

The 7th character C signals active treatment of a type III open fracture. The operating surgeon assigns the Gustilo grade, and the coder never infers it.

S82.456C is billable for FY2026, the fiscal year running from October 1, 2025 through September 30, 2026.

Pabau’s claims management software integrates with Claim.MD to validate ICD-10 codes and submit claims electronically to thousands of US payers.

ICD-10 code S82.456C is a billable code for a nondisplaced comminuted fracture of the fibular shaft, side unspecified. It applies at an initial encounter for an open fracture graded Gustilo type IIIA, IIIB, or IIIC. The 6 in S82.456 is the unspecified-laterality option, which rarely survives an audit on a high-energy open fracture.

This guide breaks the code down character by character. It covers the fibular shaft anatomy and the Gustilo grading that drives the 7th character. It also walks through the sibling codes you should usually pick instead, and the documentation a clean claim needs.

ICD-10 code S82.456C: Quick reference

The table below carries the complete quick-reference data for ICD-10 code S82.456C.

What S82.456C means, character by character

Every character in ICD-10 code S82.456C carries a specific clinical meaning. Misread one segment and the code shifts to a different bone, a different fracture pattern, or a different side of the body.

The 6th character does double duty in this family. It encodes displacement and laterality in a single digit. Characters 1, 2, and 3 are the displaced options, while 4, 5, and 6 are the nondisplaced ones.

So S82.456 sits on the nondisplaced branch, paired with the laterality the record never supplied.

Where S82.456C sits in the ICD-10-CM hierarchy

Reading the code from the top down makes the site and pattern obvious. Each level narrows the description by one attribute.

• S00-T88. Injury, poisoning and certain other consequences of external causes.
• S80-S89. Injuries to the knee and lower leg.
• S82. Fracture of lower leg, including ankle.
• S82.4. Fracture of shaft of fibula.
• S82.45. Comminuted fracture of shaft of fibula.
• S82.456. Nondisplaced comminuted fracture of shaft of unspecified fibula.
• S82.456C. The same fracture at an initial encounter, open type IIIA, IIIB, or IIIC.

The fibular shaft subcategories sit beside each other under S82.4, split by fracture pattern rather than by severity. Knowing the neighbors keeps you from landing on the wrong one when the radiology wording is loose.

None of these describe a condyle. ICD-10-CM has no fracture code for a lateral condyle of the fibula, because the fibula has no condyle. Condyle fracture codes belong to the tibia (S82.12- and S82.13-), the femur (S72.42-), and the humerus (S42.45-).

Laterality: Why unspecified is the weak point in this code

S82.456C is valid and billable, but it is rarely the code your documentation actually supports. A Gustilo type III open fracture means a large wound, a trip to the operating room, and an operative report. Reports like that almost always name the side.

The ICD-10-CM Official Guidelines are explicit on this point. Where a code offers laterality and the record does not state a side, the unspecified option is assigned. It is a last resort after a provider query, not a shortcut past one.

Payers treat unspecified laterality on a surgical trauma claim as a documentation failure. Many will deny or pend the claim for records. Auditors flag the same pattern, because the chart usually contains the answer the coder did not use.

S82.456C compared with its closest sibling codes

The six base codes under S82.45 differ only by displacement and side. The table shows all of them with the C extension applied, so the comparison is like for like.

Two neighbors outside the S82.45 family also get confused with this code. S82.446C is the nondisplaced spiral pattern, and S82.466C is the nondisplaced segmental pattern. Both share the shaft site and the unspecified side, so only the radiologist’s pattern wording separates them.

The 7th character: A through S on S82.456

The 7th character extension is where most S82.456 coding errors happen. It captures the encounter type and, for open fractures, the Gustilo-Anderson grade. The FY2026 tabular list sets all 16 options, and they fall into a pattern once you stop reading them as a flat list.

One audit trigger shows up again and again. Coders drop the C on a follow-up visit because the case feels like it moved on. Under the official guidelines, initial encounter means the patient is still under active treatment, not that this is the first visit.

A surgeon performing a second debridement in post-op week two is still delivering active treatment, so C still applies. The encounter type shifts to F only once active treatment ends and routine follow-up begins.

Gustilo-Anderson grading and the C extension

The Gustilo-Anderson system is the accepted standard for open fracture grading in ICD-10-CM. Gustilo and Anderson published it in 1976, and a 1984 revision split type III into the IIIA, IIIB, and IIIC subtypes. The operating surgeon assigns the grade, and the coder reads it from the operative report.

The same 7th character C covers all three type III subtypes. The tabular list does not separate IIIA from IIIB or IIIC at code level. That detail stays in the operative report, where it serves clinical and audit purposes.

Anatomy: The fibular shaft and comminuted fracture mechanics

The fibula runs down the lateral side of the lower leg, parallel to the tibia. Its shaft is the long middle section between the fibular neck below the knee and the flare into the lateral malleolus at the ankle. That middle section is the territory S82.4 covers.

The fibular shaft carries only a small share of body weight. Its main jobs are muscle attachment and stabilizing the ankle mortise through the interosseous membrane. It sits close to the skin along much of its length. Direct blows therefore break the bone and open the soft tissue in one go.

Comminuted means the bone broke into three or more fragments. That pattern points to a high-energy mechanism such as a motor vehicle collision, a fall from height, or a direct crush. Isolated fibular shaft fractures are less common than fractures paired with a tibial shaft injury, which is coded separately from S82.2-.

Nondisplaced comminution is an unusual combination. The bone can shatter into several pieces and still hold anatomic alignment. The interosseous membrane and surrounding muscle splint the fragments in place. The radiologist has to state it, because a payer reviewing the claim will not assume it.

One more distinction matters for coders. The nondisplaced label describes the bone fragments, not the wound. A nondisplaced fracture with a Gustilo IIIA wound is still S82.456C, and the open wound does not push it to a displaced code.

Official ICD-10-CM guidelines for traumatic fractures

Section I.C.19.c of the ICD-10-CM Official Guidelines for Coding and Reporting governs traumatic fracture coding. These are the rules that bear directly on ICD-10 code S82.456C.

• Active treatment equals initial encounter. Use 7th character A, B, or C for any encounter where the patient receives active treatment. That includes emergency department evaluation, surgery, and ongoing fracture management, whatever the visit number.
• Aftercare versus subsequent encounter. Switch to a subsequent character once active treatment ends and monitoring begins. Traumatic fractures under active treatment never take Z aftercare codes.
• Sequela coding. Use 7th character S for a late effect of the fracture. Sequence the resulting condition first, then the injury code with the S extension.
• Default to unspecified only after a query. S82.456C is the unspecified-laterality option. Query the provider first, and reserve the code for records that genuinely never state a side.
• The surgeon owns the Gustilo grade. The coder never assigns it. Without a documented grade, query the surgeon before choosing between B and C.
• Code the tibia separately. A concurrent tibial shaft fracture takes its own code from S82.2-, since S82.4 covers the fibula alone.

External cause codes to pair with the injury

Section I.C.20 of the guidelines asks for external cause codes as secondary codes alongside S82.456C. Many payers require them, and injury surveillance data depends on them. The ResDAC guide to ICD codes in Medicare files explains how they flow through claims data.

Sequence the external cause code after S82.456C on the claim. Match its 7th character to the injury code, so an initial encounter injury pairs with an initial encounter external cause.

CPT procedure codes billed alongside the diagnosis

On a surgical claim, S82.456C usually travels with fracture care and wound management CPT codes. The procedure performed drives the CPT selection, not the diagnosis code. Verify every pairing against current AMA CPT and the payer’s local coverage determinations before submission.

Reimbursement varies by payer, geography, and facility type, so treat this table as a reference rather than a fee guarantee. Building a clean superbill that carries the diagnosis and the procedure together is what keeps medical necessity denials down.

Documentation requirements for S82.456C

Incomplete documentation drives most denials on complex fracture codes. Work through this checklist before the claim leaves the practice.

• Laterality search. Check the imaging report, the operative note, and the anesthesia record for a documented side. A named side moves the claim to S82.454C or S82.455C.
• Shaft location. The radiology report should place the fracture in the fibular diaphysis. A proximal head or distal malleolar fracture belongs to a different S82 subcategory.
• Comminution. The report needs to describe three or more fragments, or use the word comminuted. Spiral and segmental wording sends you to S82.44 or S82.46 instead.
• Displacement status. Radiology must confirm the fragments remain in alignment. If they are displaced, the correct code is S82.451C, S82.452C, or S82.453C.
• Open wound description. The emergency or operative note should record wound size in centimeters, contamination level, and soft tissue involvement.
• Gustilo grade. The operating surgeon must state IIIA, IIIB, or IIIC in the operative report. Without it, 7th character C cannot be assigned.
• Encounter type. Confirm whether the visit delivered active treatment or follow-up care, since that decides between C, F, and J.
• External cause. Record the mechanism of injury, then add the matching W, V, X, or Y code and any place-of-occurrence code the payer wants.

Checklists work best when they sit inside the clinical workflow at the point of care. Applied retrospectively at billing, they turn into rework. Laterality and grading omissions on this code family come back as common denial codes weeks after submission.

Six coding errors that trigger denials

These six mistakes account for most of the denials and audit findings on this code.

• Treating S82.456 as the left fibula. Left is S82.455 and right is S82.454. The 6 is the unspecified option.
• Coding a condyle. The fibula has no condyle. Condylar fracture codes exist for the tibia, femur, and humerus only.
• Skipping the provider query. Unspecified laterality without a documented query is the finding auditors write up most often on this family.
• Confusing the pattern. Comminuted, spiral, and segmental each have their own subcategory. Copy the radiologist’s word rather than paraphrasing it.
• Dropping C too early. Active treatment keeps the C extension, including repeat debridements and staged fixation.
• Defaulting to type I. An open fracture with no Gustilo grade is not automatically type I, and B is not a safe fallback for C.

Where to verify the code before you submit

Code descriptions move between fiscal years, so check the current source before you submit. FY2026 runs from October 1, 2025 through September 30, 2026.

• CDC ICD-10-CM browser tool. The NCHS tool gives the tabular list and index for the active fiscal year.
• CMS ICD-10 codes page. The CMS release files carry the annual code updates and addenda.
• ICD-10-CM Official Guidelines. Section I.C.19 covers injury and fracture coding, including the 7th character rules.
• AHA Coding Clinic. The recognized source for query practice and for advice on ambiguous fracture documentation.
• AAPC Codify. The ICD-10-CM lookup is useful for browsing the full S82.456 variant list.

How Pabau keeps fibula fracture coding tied to the claim

In most practices the side of the injury is recorded once, in the imaging report, and then re-keyed by hand at billing. That hand-off is where S82.455C quietly becomes S82.456C, and the denial arrives three weeks later.

Practice management software like Pabau keeps the clinical record and the claim in the same system. Laterality, the fracture description, and the operative note stay attached to the encounter, so the biller codes from the chart instead of a summary.

Pabau’s claims management software then validates diagnosis and procedure codes before submission. Our Claim.MD integration reaches thousands of US payers electronically. Mismatches surface while you can still fix them, so fewer trauma claims come back for records.

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Conclusion

ICD-10 code S82.456C describes a nondisplaced comminuted fracture of the fibular shaft. It applies at an initial encounter, with a Gustilo type IIIA, IIIB, or IIIC open wound. Three details have to line up in the record: the shaft site, the comminuted and nondisplaced pattern, and the surgeon’s Gustilo grade.

The fourth detail is the one that decides the claim. S82.456C carries unspecified laterality, so it is the code you use when the chart never named a side. Check for one first, because S82.454C or S82.455C is usually the code the documentation supports.

Keeping laterality and fracture detail attached to the encounter is a workflow problem more than a coding one. To see how Pabau handles it for orthopedic and trauma billing, book a demo.

Continue your research

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